scholarly journals A permeation-diffusion-reaction model of gas transport in cellular tissue of plant materials

2006 ◽  
Vol 57 (15) ◽  
pp. 4215-4224 ◽  
Author(s):  
Q. T. Ho ◽  
B. E. Verlinden ◽  
P. Verboven ◽  
S. Vandewalle ◽  
B. M. Nicolai
Keyword(s):  
Gas Transport ◽  
Cellular Tissue ◽  
Reaction Model ◽  
Diffusion Reaction ◽  
Plant Materials

Diffusion-reaction model for ASR

2014 ◽  
pp. 639-648 ◽  
Author(s):  
J Liaudat ◽  
C López ◽  
I Carol
Keyword(s):  
Reaction Model ◽  
Diffusion Reaction

scholarly journals Fractal diffusion-reaction model for a porous electrode

2021 ◽  
pp. 26-26
Author(s):  
Ling Lin ◽  
Yun Qiao
Keyword(s):  
Surface Morphology ◽  
Porous Electrode ◽  
Enzymatic Reaction ◽  
Bright Light ◽  
Reaction Model ◽  
Solution Procedure ◽  
Diffusion Reaction ◽  
Fast Diffusion ◽  
Fractal Derivative ◽  
Intuitive Grasp

Fractal modifications of Fick?s laws are discussed by taking into account the electrode?s porous structure, and a fractal derivative model for diffusion-reaction process in a thin film of an amperometric enzymatic reaction is established. Particular attention is paid to giving an intuitive grasp for its fractal variational principle and its solution procedure. Extremely fast or extremely slow diffusion process can be achieved by suitable control of the electrode?s surface morphology, a sponge-like surface leads to an extremely fast diffusion, while a lotus-leaf-like uneven surface predicts an extremely slow process. This paper sheds a bright light on an optimal design of an electrode?s surface morphology.

Multiscale homogenization for fluid and drug transport in vascularized malignant tissues

2014 ◽  
Vol 25 (01) ◽  
pp. 79-108 ◽  
Author(s):  
R. Penta ◽  
D. Ambrosi ◽  
A. Quarteroni
Keyword(s):  
Drug Transport ◽  
Reaction Model ◽  
Diffusion Reaction ◽  
Momentum Balance ◽  
Cancer Therapies ◽  
Multiscale Expansion ◽  
Anti Cancer ◽  
Intercapillary Distance ◽  
Multiscale Homogenization

A system of differential equations for coupled fluid and drug transport in vascularized (malignant) tissues is derived by a multiscale expansion. We start from mass and momentum balance equations, stated in the physical domain, geometrically characterized by the intercapillary distance (the microscale). The Kedem–Katchalsky equations are used to account for blood and drug exchange across the capillary walls. The multiscale technique (homogenization) is used to formulate continuum equations describing the coupling of fluid and drug transport on the tumor length scale (the macroscale), under the assumption of local periodicity; macroscale variations of the microstructure account for spatial heterogeneities of the angiogenic capillary network. A double porous medium model for the fluid dynamics in the tumor is obtained, where the drug dynamics is represented by a double advection–diffusion–reaction model. The homogenized equations are straightforward to approximate, as the role of the vascular geometry is recovered at an average level by solving standard cell differential problems. Fluid and drug fluxes now read as effective mass sources in the macroscale model, which upscale the interplay between blood and drug dynamics on the tissue scale. We aim to provide a theoretical setting for a better understanding of the design of effective anti-cancer therapies.

scholarly journals Effective and Apparent Diffusion Coefficients of Chloride Ions and Chloride Binding Kinetics Parameters in Mortars: Non-Stationary Diffusion–Reaction Model and the Inverse Problem

Materials ◽  
2020 ◽  
Vol 13 (23) ◽  
pp. 5522
Author(s):  
Jerzy Jasielec ◽  
Jakub Stec ◽  
Krzysztof Szyszkiewicz-Warzecha ◽  
Artur Łagosz ◽  
Jan Deja ◽  
...  
Keyword(s):  
Diffusion Coefficients ◽  
Reaction Model ◽  
Chloride Ions ◽  
Diffusion Reaction ◽  
Chloride Diffusion ◽  
Accurate Estimation ◽  
Chloride Binding ◽  
Apparent Diffusion Coefficients ◽  
Binding Isotherms ◽  
Apparent Diffusion

A non-equilibrium diffusion–reaction model is proposed to describe chloride transport and binding in cementitious materials. A numerical solution for this non-linear transport with reaction problem is obtained using the finite element method. The effective chloride diffusion coefficients and parameters of the chloride binding are determined using the inverse method based on a diffusion–reaction model and experimentally measured chloride concentrations. The investigations are performed for two significantly different cements: ordinary Portland and blast furnace cements. The results are compared with the classical diffusion model and appropriate apparent diffusion coefficients. The role of chloride binding, with respect to the different binding isotherms applied, in the overall transport of chlorides is discussed, along with the applicability of the two models. The proposed work allows the determination of important parameters that influence the longevity of concrete structures. The developed methodology can be extended to include more ions, electrostatic interactions, and activity coefficients for even more accurate estimation of the longevity.

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